A hole cutter, hole saw, or cup saw, is a type of cutter used in drilling circular holes in various materials, such as wood, metal, drywall, etc. A hole cutter typically has a substantially cylindrical body that defines a side wall and a hollow interior within the side wall, a circular cutting edge with multiple teeth located at one end of the body that are designed to cut a work piece during rotation of the cutter, and a cap located at the end of the body opposite the cutting edge for attaching the hole cutter to a driving device, such as a drill or other motorized device. The cap typically includes threads, holes or other structure adapted to allow the hole cutter to be drivingly connected to a drill, such as through an arbor. In use, the circular cutting edge can create a circular hole in a work piece and, in turn, can remove a circular work piece slug therefrom. Typically, after the hole is cut in the work piece, the work piece slug is retained within the hollow interior of the hole cutter and must be removed therefrom prior to cutting another hole.
Some conventional hole cutters can include apertures or slots formed in the side walls of the hole cutters that allow users to insert a lever, such as a screw driver, through the side wall and into the interior of the hole cutter to, in turn, lever or otherwise urge the slug out of the hole cutter. This slug removal task can be time-consuming and take substantial effort on the part of the user. A slug may be difficult to extract from within the body of a cutter, even with a hole cutter that includes slug removal apertures or slots, because the slug can become tightly wedged in the cutter or because the slug removal apertures or slots are not aligned with the slug. For example, a slug may become warped or cracked and thus, firmly lodged within the hole cutter. As another example, some work pieces, such as certain wood or wood-based products, contain saps or other sticky or glue-like residue that inhibits slug removal.
In addition, thicker and thinner work pieces can create slugs of differing thicknesses and slugs positioned at different locations within the hollow interior of the hole cutter. For example, a thick work piece can create a thick slug that can be pushed deep into the hollow interior of the hole cutter, whereas a thin work piece can create a thin slug located within the hollow interior of the hole cutter near the cutting edge. Accordingly, slugs often do not simply “pop” out of the cutter when worked by a tool. Slugs often slide short distances, twist, tilt, or otherwise gradually or incrementally move along the hollow interior of the hole cutter. The apertures in the side walls of conventional hole cutters can be relatively short in length or in respect to the vertical distance between the cutting edge and the cap, and therefore may be used only to remove either relatively thin or relatively thick work piece slugs, but not both types of slugs, and possibly not slugs of medium thicknesses. Further, the relatively short vertical length of these apertures may allow for moving of the slug through a certain portion of the hollow interior of the hole cutter but not through the entirety of the hollow interior and out of the hole cutter at the cutting edge. Other conventional hole cutters have multiple apertures that are axially and angularly spaced relative to each other, wherein each aperture is relatively short in length. U.S. Pat. Nos. 8,579,554 and 8,579,555, which are incorporated herein by reference, show hole cutters with apertures in their sidewalls with multiple fulcrums.